1. Field of the Invention
The present inventive concept relates to an image forming apparatus which forms an image on a printing medium, and more particularly, to an image forming apparatus which improves an arrangement configuration of a main board and a high voltage power supply, and a connection configuration between a sub electronic element and various boards.
2. Description of the Related Art
As illustrated in FIG. 1, an electrophotographic image forming apparatus includes a developing unit 10 having a photosensitive medium 11, a light scanning unit 20, a feeding unit 30, a transfer unit 50 and a fusing unit 60. The light scanning unit 20 scans light to the photosensitive medium 11 charged with a predetermined electric potential by a charging roller 13 to form an electrostatic latent image on the photosensitive medium 11. The developing unit 10 develops the electrostatic latent image with a predetermined color toner to form a visible image on the photosensitive medium 11. Then, the transfer unit 50 and the fusing unit 60 respectively transfer and fuse the visible image on a printing medium fed by the feeding unit 30 to print an image on the printing medium P.
The feeding unit 30 includes first and second cassettes 31 and 35 which are provided below a cabinet 1 of the image forming apparatus, and a multi-purpose printing medium feeding tray 41 which is provided at a lateral side of the cabinet 1.
The first and second cassettes 31 and 35 may include a sensor to detect a residual amount of a printing medium P stored therein, to detect the supply of the printing medium P and to register a front end of the printing medium P, and a sub electronic element having a driving circuit.
As illustrated in FIG. 2, a conventional image forming apparatus includes a printing engine (not illustrated), an engine frame 110 which supports the printing engine and has a driving system and various sensors, a main board 120 which controls a video signal and the printing engine, and a control panel display unit 130 which is provided to control a control panel.
The printing engine includes the photosensitive medium 11, the charger 13 which forms the electrostatic latent image and the visible image on the photosensitive medium 11, the light scanning unit 20 and the developing unit 10 as illustrated in FIG. 1. The printing engine further includes the transfer unit 50 which transfers the visible image formed on the photosensitive medium 11 to the printing medium P, and the fusing unit 60 which fuses the visible image transferred to the printing medium P.
The conventional image forming apparatus further includes a high voltage power supply (HVPS) 140 which is electrically connected with the main board 120 and applies a high voltage to the developing unit 10, the charger 13, the transfer unit 50 and a static eliminator.
The engine frame 110 includes a first detecting sensor 111 which detects whether the printing medium P is stored in the first cassette 131 (refer to FIG. 1), a feeding sensor 113 which detects the supply state of the printing medium P, an MP detecting sensor 115 which detects the printing medium P in the multi purpose tray 41, a first pickup solenoid 117 which is provided to pick up the printing medium P, and a driving motor 119.
The main board 120 includes a system engine controller 121, a video controller 123 which controls a video signal, and a memory 125 which stores information therein to form an image. The system engine controller 121 controls the engine frame 110, the control panel display unit 130, the high voltage power supply 140 and the sub electronic elements of the second cassette 150. The second cassette 150 includes the sub electrode elements, i.e. a second detecting sensor 151 which detects whether the printing medium P is stored in the second cassette 150, and a second pickup solenoid 153. The memory includes a flash memory, a DRAM (dynamic random access memory), an EEPROM (electrically erasable programmable read-only memory), etc.
As illustrated in FIG. 2, sub electronic element control signal lines are additionally connected between the main board 120 and the engine frame 110 of the conventional image forming apparatus. Thus, the configuration of the sub electronic element control signal lines becomes complicated, thereby requiring more space.
As the sub electronic elements of the first and second cassettes 131 and 150 are directly connected with the main board 120, the connection line therebetween extends depending on a position of the main board 120, thereby raising costs. Also, the sub electronic elements are difficult to replace, assemble and disassemble.
As the respective sub electronic elements are directly connected with the main board 120, noise signal components such as static electricity generated during the printing medium feeding process are also directly transmitted to the main board 120, thereby lowering reliability of the connection.